TMR sensor with a multilayered reference layer

1. A method for forming at least a portion of a magnetic head, the method comprising:

forming a keeper layer;

forming a reference layer;

forming an AFM coupling layer, the AFM coupling layer being positioned between the keeper layer and the reference layer; and

wherein forming the reference layer includes:

forming a layer of CoFe;

depositing a layer of CoFeHf, wherein the layer of CoFeHf is about 20 atomic % Hf;

depositing a layer of CoFeB, wherein the layers of CoFeHf and CoFeB are directly adjacent; and

depositing a second layer of CoFe above the layers of CoFeHf and CoFeB.

2. The method as recited in claim 1 , wherein depositing the layer of CoFeHf is performed by co-sputtering CoFe and Hf, wherein a Hf and a CoFe deposition power are each selected and used to provide a HeP 2 of the reference and keeper layers of greater than about 3500 Oe.

3. The method as recited in claim 1 , wherein depositing the layer of CoFeHf is performed by sputtering from a CoFeHf target, wherein the CoFeHf target provides a HeP 2 of the reference layer and keeper layer of greater than about 3500 Oe.

4. The method as recited in claim 1 , wherein depositing the layer of CoFeHf is performed by co-sputtering CoFe and Hf, wherein a Hf and a CoFe deposition power are each selected and used to provide a HeP 1 of the keeper layer and an antiferromagnetic layer of greater than about 5900 Oe.

5. The method as recited in claim 1 , wherein depositing the layer of CoFeHf is performed by sputtering from a CoFeHf target, wherein the CoFeHf target provides a HeP 1 of the keeper layer and an antiferromagnetic layer of greater than about 5900 Oe.

6. The method as recited in claim 1 , wherein depositing the layer of CoFeHf is performed by co-sputtering CoFe and Hf, wherein depositing the layer of CoFeB is performed by sputtering, wherein a ratio of respective physical thicknesses of CoFeHf to CoFeB is less than about 0.66.

7. The method as recited in claim 6 , wherein the ratio of respective physical thicknesses of CoFeHf to CoFeB is less than about 0.33.

8. The method as recited in claim 1 , wherein depositing the layer of CoFeHf is performed by sputtering using a CoFeHf target, wherein depositing the layer of CoFeB is performed by sputtering, wherein a ratio of respective physical thicknesses of CoFeHf to CoFeB is less than about 0.66.

9. The method as recited in claim 8 , wherein the ratio of respective physical thicknesses of CoFeHf to CoFeB is less than about 0.33.

10. The method as recited in claim 1 , wherein a ratio of respective physical thicknesses of CoFeHf to CoFeB is greater than 0 and less than or about 0.22.

11. A method for forming at least a portion of a magnetic head, the method comprising:

forming a keeper layer;

forming a reference layer;

forming an AFM coupling layer, the AFM coupling layer being positioned between the keeper and reference layers; and

wherein forming the reference layer includes:

forming a layer of CoFe;

depositing a layer of CoFeHf, wherein depositing the layer of CoFeHf is performed by co-sputtering CoFe and Hf or by sputtering from a CoFeHf target; and

depositing a layer of CoFeB, wherein depositing the layer of CoFeB is performed by sputtering,

wherein the layers of CoFeHf and CoFeB are directly adjacent, and wherein a ratio of respective physical thicknesses of CoFeHf to CoFeB is less than about 0.22 and greater than 0.

12. The method as recited in claim 11 , wherein depositing the layer of CoFeHf is performed by co-sputtering CoFe and Hf, wherein a Hf and a CoFe deposition power are each selected and used to provide a HeP 2 of the reference and keeper layers of greater than about 3500 Oe.

13. The method as recited in claim 11 , wherein depositing the layer of CoFeHf is performed by sputtering from a CoFeHf target, wherein the CoFeHf target provides a HeP 2 of the reference and keeper layers of greater than about 3500 Oe.

14. The method as recited in claim 11 , wherein depositing the layer of CoFeHf is performed by co-sputtering CoFe and Hf, wherein a Hf and a CoFe deposition power are each selected and used to provide a HeP 1 of the keeper layer and an antiferromagnetic layer of greater than about 5900 Oe.

15. The method as recited in claim 11 , wherein depositing the layer of CoFeHf is performed by sputtering from a CoFeHf target, wherein the CoFeHf target provides a HeP 1 of the keeper layer and an antiferromagnetic layer of greater than about 5900 Oe.

16. The method as recited in claim 11 , further comprising forming a ferromagnetic layer above the layer of CoFeB and below a dielectric tunnel junction layer.

17. The method as recited in claim 11 , wherein a ratio of respective deposition times of CoFeHf to CoFeB is about 0.22 or less and greater than 0.

18. The method as recited in claim 11 , wherein the layer of CoFeHf is about 20 atomic % Hf.

19. A magnetic head, comprising:

a keeper layer;

an AFM coupling layer adjacent the keeper layer;

a reference layer on an opposite side of the AFM coupling layer than the keeper layer, the reference layer further comprising:

a layer of CoFe;

a layer of CoFeHf; and

a layer of CoFeB, wherein the layers of CoFeHf and CoFeB are directly adjacent;

a free magnetic layer; and

a dielectric tunnel junction layer between the free magnetic layer and the reference layer,

wherein the layer of CoFeHf is about 20 atomic % Hf, and

wherein a ratio of respective physical thicknesses of CoFeHf to CoFeB is less than about 0.22 and greater than 0.

20. The magnetic head as recited in claim 19 , further comprising an antiferromagnetic layer positioned below the keeper layer, wherein a HeP 2 of the reference and keeper lavers is greater than about 3500 Oe, and wherein a HeP 1 of the keeper layer and the antiferromagnetic layer is greater than about 5900 Oe.

21. The magnetic head as recited in claim 19 , wherein a HeP 2 of the reference and keeper layers is greater than about 3500 Oe.

22. The magnetic head as recited in claim 19 , wherein a HeP 1 of the keeper layer and an antiferromagnetic layer is greater than about 5900 Oe.